Improvement in computing-apparatus



'tibi-imi. gltig ELIZR WRIGHT, OF MEDFORD, MASSACHUSETTS.

.Trailers Patent N 93,849, dll-ted August 1T, 1869.

IMPROEMENT IN COMPUTING-APPARATUS.

The Schedule referred to in these Letters Patent and making part of the same.

To all whom "it may concern Be it known that I, ELrzUrr Hutu-rr', of Medford, in the county of Middlesex, and Stateot' Massachusetts, have invented an Arithrneter; and I do hereby declare that the following, taken in connection with the drawings which accompany and form part ofthis specification, is a description of my invention, sufficient to enable those skilled irr the art to practise it.

'lhis invention relates to the construction ol' a meehanisrn or" apparatus for performing ar'itlnnetical operations without mental process.

The construction ot' slide-rules, and other scales for solving questions of' multiplication and divisioutof numbers by logarithmic proportions, is well known, such scales having division-lines and nurrrber's engraved nporr them, by means of which arithrnetical results are obtained by inspection, and the use, in connection, of conrpasses or gauges stretching from division' to divrsron. y

My improvement has particular reference to such an arrangementof the numbers and divisions ot' the respective scales as shall enable any factor' of each scale to be brought into position, with relation to the sliding index or pointer', so that the result of the problem can be read by the position of an auxiliary pointer; and

The invention consists, primarily, in two rotar'y cylinders or disks, upon the surface of each of which the logarithmic scale is ma-rked and numbered upon spir'al or helical Iirrcs r'urrnirrg rnany times around the cylindric surface ot' each cylinder', or the flat surface of each disk, these cylinders or disks having rotary movement, with r'espectrto a stationary arm orbar, carrying sliding pointers for marking the factors and designating the result.

I term this instrument a-n Arithmeten and thc drawings represent a machine embodying the invention.

A shows a front elevation of the arithnretcr.

B, au end view of it..

C, a vertical cerrtr'al longitudinal section of it.

a a denote two standards, haring, at top, bearings b for supporting a shaft, c.

On this shaft, between thc standards, are mounted the two cylinders l e, one of which (d) is fast upon the shaft, while the other can slip or rotate upon the shaft. i

The cylindrical surface of each cylinder is covered with a paper' coating, connected thereto, and around Athis surface is dr'awn a spiral li'ne, (or two adjacent par'- :rllel .spiral lines,) running from one end of the cylinder to the other', starting at a point at one end ofthe cylindcr, at the edge of the paper' surface, and r'urrning spirally around, until the opposite end of the cylinder' he reached, the distance between thc adjacent lines of the spiral being uniform throughout, and the total length of the spiral being determined hy the angle or pitch given to it.

'lhe spiral lines of the two `cylinders exactly corr'csporrd, and, atter they are drawn, each is divided (preferably by means of a temporary peripheral scale, of equal parts, around the head ot` one of the cylinders) into logarithmic divisions, the two scales thus made corresponding in their divisions, and cach being ot' a great and continuous length, equal to the circurnt'er# enceof the cylinder, multiplied by the numbcrof times the spiral surrounds the cylinder.

From the top of the two standards af, two armsf extend out to the surface ofthe cylinder", and sustain, at their' outer ends, .frI cross-bar', y, which extends across the surface of hoth'cylinder's, its upper' edge serving as a straight-edge. down to or-opposite which the re spective` divisions of the scalo to be read, serving as factors, a-r'e brought, and over which the result is read.

This ba-r is made with guide-grooves, in which moves a slide, Ii, upon one end of which is a point-er, 7.', the outer edge of whichrwhen the pointer is moved up to its normal position, comes opposite the first division of' the scale.v

In the face of the slide -i is a guide-slot, l, in which runs a. slide, fm, bearing at its opposite ends two pointer's n o.

Each slide may have a knob, 1), by which to move it.

The slide lm is provided with a suitable spring, fixed to or projecting from it, and bearing against the slide i, with stress suticient to hold it stationary, with respect t the slide li, when the latter is moved.

The head of the cylinder (l is provided 'with a gear'- wheel, j, into which meshes a driving-pinion, q, on the end of a shaft, 1', jonrnalled'in a bearing fixed upon the adjacent arm f, aud having at its outer end a handle, s.

lhc head ot' the other cylinder c, has, projecting in war'dly from it, a shortl hub, s, which is embraced by spr'ings t projecting from a quill, '11, on the shaft c, the pressure ,of these springs being sulicicnt to cause the two cylinders :to rotate together', (or as one,) unless the cylinder' c is held by some brake-mechanism.

lhe standard a, adjacent to the cylinder' c, has in its inner' side a vertical slot, in which is a rod, fv, at the foot of which is a brake-shoe, n', which -projects under' the edge of the cylinder-head, and is pressed upward by a suitable springer springs.

Over' the top of the rod c is an eccentric, x, on the end of a thumb-shaft, y, passing through the standard.

By turning the thumb-shaft, and causing the eccentr'ic to press down the rod, the brake-shoe is carried out of contact with the edge of the cylinder-head, when the cylinder e will turn with the cylinder d, while by turningr the eccentric, so as to let the springs throw the brake up against the edge of the cylinder-head, the cylinder c will be arrested, so that rotary motion of the cylinder d imparts no movement to the cylinder c.

'Io operate the instrument, eit-her for multiplication or division, it is first to be observed, that of the three pointers, that at the right, which slides in the crossbar y, belongs altogether to the right-hand cylinder, or d, and the other two, which'slidc in the slide fi, belong altogether to the left-hand cylinder e; but only one of them indicates at the same time, because whenever one slides opposite the scale, the other slides ofi'.

To .multiplyz Allow the cylinder e to revolve, find on it one of the factors, or as many as you can of the lefthand tigures of it, bring it to the cross-bar, and fix that cylinder by a quarter of a turn of the thumbshaft y. Then bring the unit, or beginning of the scale, on the other oylinderd, to the cross-bar, and set the pointer toit, while you set the extreme left-hand pointer n to the factor already found on cylinder c.- 'Ihen take oii the brake, and turning the two cylindels as one till the other factor ,on cylinder d comes to the 'cross-bar, slide the pointer 7c to it, and whicheyer of the other pointers, -n or o, is opposite the scale ou cylinder e, will indicate the product, or the lett-hand tigures of it. ,1f the factors contain more than the figures marked on the scale, they may be divided into convenient portions, and multiplied as polynomials.

Io divide: Find the dividend on c, bring it t-o the cross-bar, and fix that cylinder. `Then find the divisor on d, bring it to the cross-bar, and slide the pointers so that L will point to the divisor and o to the dividend, if the space is not too great, but -n if it is. Then release cylinder e from thebrake, turn the cylinders as one till the unit of d is at the cross-badanti slide k to it. The quotient will be found on cylinder e, indicated by whichever of the pointers n, or o, is opposite the scale., Y

By this means, as will bc obvious to persons acquainted with the use of logarithmic scales, operations of multiplication and division may be veryspeedily performed, without mental calculation or the use of iiguring, lthe instrument being of manifest utility in all oiiices where, in the preparation of statistical tables, such results have to be constantly obtained.

The specific description has had reference to a spiral scale, made around the surface of a cylinder; but it will be obvious that a similar result may be attained by employing two consecutive disks or rings, having the scale-lines running helically around the face of each, a radius-bar serving as a bed for the pointerslides, and as a straight-edge, against which to bring and read the divisions; but I prefer the construction of the instrument as shown.

- I claim, in combination with suitable pointing-mechanism, two cylinders or disks, on the same shaft, and operated by the same driver, one being driven by ii'ictional contact with the other, and both having logarithmic divisions, marked upon coiled or helical lines drawn upon their-surfaces, substantially' as shown and described.

I also claim, in combination with cylinders, so arranged, lined, and divided, the stationary bar g,and

the pointer-slides n o, substantially as shown and' described.

I also claim, in combination with the cylinders, both operated from the same common driver, devices for effecting the rotation of both together, or of only one at option, substantially as shown and described.

' ELIZUR WRIGHT.

W'itnesses:

H. A. BROWN, WALTER 0.7WnIGH'r. 

